Got a phone call from my boys father. He wants me to come back before our son is born. He wants to…

Got a phone call from my boys father. He wants me to come back before our son is born. He wants to have us sign an agreement in which if i leave he gets my son if he leaves i get my son. So i have a "reason" to stay. I told him my son isnt a bargin deal or leverage over someone. I wasnt gunna sign something like that. Told me that he is my worst nightmare and that he can afford a better lawyer then i ever could. You want me to come back then u use our son as leverage then tell me you can do better then me to get custody? Wtf?